Alpha-amino,4, 6, 6-trimethyl heptanoic acid



Strecker hydantoin route, or the older Lim- Patented Sept. 3%, 1952 4 umrzzoflsmres PATENT Eii ALPHA-AMINO,4,6,6-TRIMETHYL HEPTANOIC ACID 3 Robert Neal MacDonald, Wilmington, DeL, as-

signor to E. I. du Pont de Nemours and'Company, Wilmington, DeL, a corporation of Delawere m No Drawing. Application July 9, 1951, f Serial No. 235,900 r l p 1 1 Claim. (01. 260-534) j c a l ,y 2 This invention relatesto a new alpha-amino acid and is a continuation-in-part of my copending application Ser. No. 778,459, filedOctober 7, 1947.

weight are illustrative of the, invention.

' EXAMPLE I Many alphaaminocarboxylic acids are w'ell 5 Preparationof 5-(2,4, 4-triknown in the art. includingsome of relatively r newt/196M11 fl fl high carbon content. However, these acids, pari CH; CH3 i ticularlythose of relatively long chain structure; l l d gg have thus far been prepared from relatively ex- I NH N pensive and not readily available intermediates. 1 For instance, U. S. 2,109,929 teaches the prepa'rf CH3 C 3 ation of long chain hydrocarbon alpha-monoaminomonocarboxylic acids of from 8 to 18 chain CH V v v H carbons by the amination with liquid ammonia r 3 J 1 of the corresponding alphahalo acids. These 1 v t E Q alpha-halo acids are relatively expensive and To a Solution of. 142 tf 5 5 t 1 not readily v a 1101 can y-b P p .hexanal in 545 parts of ethanol was added a from cheap or readily available.intermediates. mm of 0 parts of 1 1 i i This invention as s an j ct th pr par 180 parts of water...As the reaction mixture tion of a newl alpha aniino carboxylic acid. A 20 was ti d at 15 0., 515 parts of 95% sodium f t r e t t e reparation'of such a acid cyanide. in 150 parts of water was added during from cheap andava'ilable raw materials. Other objects will appear hereinafter. I V then stirredatroom temperature for three hours;

These objects are accomplished by the prepara- .250. parts of, '(NH4)2CQ3-H2O was added; and i n 2- min0-. ,6trimctl'lylheptanoic acid. stirring was continued at 55-60 C. for four This acid can easily be pr'epared,.e. g. by the 7 hours. Excess ammonium carbonate waswdecomposed at steam bath temperature, the repricht cyanohydrin/aminonitrile route. fpreferaction mixture repeatedly concentrated and ably the former, from 3,"5,5 trimethylhexanal, cooled until no further precipitate formed, and which in turn can be prepared by the direct the crude hydantoin filtered off at each stage; reaction of. diisobutylene with carbon monoxide Thecombined precipitates were dissolved in'5% and hydrogen in the mannergdisclosed in III S. aqueous Sodium dr xid and extracted r l 4 7 times with etherto remove unreacted aldehyde. 'I'his alpha-amino carb oxyuc acid is not Was decololized only, readily preparable and of-relative1y l activated charcoal and the hydantoin preeipi cost but surprisingly has many unique properrecrystallization from alcohol water there was certamly not'predmtable mm the pmrart obtained 142 parts (67% of theoret ical) or white nor aconsideration of its structure. In the first I place,' this new alpha-amino acid exhibits an crystals of pure l d neffect on the surface tension of aqueous solutions 40 tom memngap 189-190 of the'same order as many commercial surface- (B) Preparation of 2-Ammo-4,6,6-trimetiiylactive age'nts'fl "Incontrast, the known straight heptanoic acid i chain isomer,"alpha-aminocapric' acid, exhibits 1 ([3113 1 y no appreciable surface tension efiect on aqueonlo-omon oniori-wo ous solutions and in fact is difficultlysolubl v E3 in even basic; aqueous systems. Furthermore; 6073112804 v this new alpha-amino acid exhibits burn and v O reflux formative effects "on tomato plants; whereas the V t straight chain isomer, alpha-aminocapric acid, exhibits no effects whatever in such tests. v c

M The following examples in which parts are by a half-hour period. The. reaction mixture was tated by acidifying with hydrochloric acid. After i l y Y 1 onso -onionwmorrooon Onehundred and fifty parts of -(2,4,4-trimethylpentyDhydantoin was hydrolyzed by refluxing for two days with 450 parts of60 sulfuric acid. The hydrolysis mixture was diluted with 600 parts of water and decolorized with activated charcoal. After the addition of ammonium hydroxide until a pH of 6 was reached, the resulting precipitate of the amino acid was filtered, washed once with water, and

dissolved in 5% sodium hydroxide. The resulting solution was decolorized with charcoal and brought to a pH of 6 by controlled addition of hydrochloride acid. The precipitated amino acid was filtered and washed until the wash water:

gave a negative chloride test with silver nitrate.

Concentration of the wash water gave another small yieldof product. The products werec'ombined and recrystallized from a large" quantity ofhot water. There was obtained 123 parts (92% of theory) of pure crystalline. 2-ainino- 4,6,6 -trimethylheptanoic acid melting withudecomposition at 228-230" C. Neutral equivalentcalculated, 187.3; found, 1896.

. The aminoacid was characterized through its trimethylheptanoic acid, melting at 138-14 0 -C. Neutral equivalent-calculated, 291.38; found,

The amino acid canbe readily converted to its acid, e. g. hydrohalide, addition salts through the amine group and its alkali forming'metal, i. e., alkali metal andalkaline earth metal, salts through the carboxyl group. Thus the hydrov chloride can'be prepared by adding concentrated hydrochloric acid in perhaps 10% excess to a hot, 3 to 5%, aqueous solution of the amino acid and'evaporating to dryness. can be prepared by adding an equivalent amount of aqueuos sodium hydroxide solution to a hot,

3 to 5 %L aqueous solution of the-am'inoacid and evaporating to dryness, or precipitating the sodium salt by addition-of excess alcohol! The barium saltcan be prepared by-adding an equivalent amount of bariumhydroxide solution to. a hot aqueous solution of the acid mid -evaporating' to dryness or 'precipitatingthe bariuni salt by addition ofalcohol. "For the purposes ofthis invention the alkali forming-metal salts (through the carboxyl group) and the hydrohalide salts (through the-amino group) are regarded as -equivalentsof the acid.- a -i J k' lhe "surface activity of. this "newamino' acid .wasevaluated by dissolving 0.5 g.',g san pl es of the Ka'cid' in; respectively, 26.7 cc." 'of .'aqueous 0.101 hydrochloric acid and sodium hydroxide solutions, diluting 'hoth'solutionsfto 190., ml. with distilled water, and determining the surface. tension of the resultin solutions usin -a "Roller- Smithsurface tension balance; fl'heaciidic solution' exhibited a surface tension of 37.24

dynes/cm. and the basicgs'olution a: surface ten-'- sion of 41.04 dynes/cm. In "contrastfcontrol solutions containing no added amino acid exhibited surface tensions :of 556.28 and 56.95 dynes/cm. for, respectively, the acidic and basic solutions. Furthermore, similar solutions made up substituting 9.5 g. samples of the isomeric alpha-aminocapric acid for the 2- amino-4,6,6- trimethylheptanoic acid exhibited surface tensions of 49.89 and 51.74 dynes/cm. for, respectively, the acidic and basic systems. Thus, it can be seen that the straight chain IO-carbcn alpha a'mino acid exhibits no significant surface The sodium salt I v did the alpha-aminocapric solve.

' 4 y activity; whereas the new 2-amino-4,6,6-tri methylheptanoic acid surprisingly exhibits relatively high surface activity. In fact, the values exhibited by this new alpha-amino acid are in the range of those exhibited at these concentrations by the majority of surface-active agents. See, for instance, page 282 of Schwartz and Perry, Surface-Active Agents, Interscience, 1949. It

should be" noted that in neither theacidic nor basic solutions at the extremely low concentrations involved, and even at lower concentrations (0.25 g. of amino acid/100 ml. of solution),

acid completely dis- EXAlVIPLE III preciably more noticeable. Furthermoreyatithls '7 concentration a slightburning of the leaves: was noted." In surprising contrast, aqueous systems 'of "the isomeric alphasaIniriqiiapric acid exhibited no noticeable effects whatever when sprayed' on I tomato :plantsat cencentrations as high as 10 ofthe amino acid. Thus, the "new 2amino-i,6,6-trimethylheptanoicacid represents a relatively cheap and easily prepared alpha-aminocarboxylic acid of relatively high carbon content which is useful as a surfaceactive agent foraqueous systems and j a plant growth regulant, particularly the former. v The 'alkaliformihgjmetal,"i. e., alkali and alkaline earth metal salts through. m agrboxyl group and the hydrohalide addition salts through the amino group are readily and easily prepared by methods well .known in the art and are equally useful "as surface activeagents, particularlythe moresolubl'e alkali metal'and hydrohallde'salts. f

a'rnav t is w -annmmianib1s maeceller'itsurface-ractive eifectsin aqueous systems is particularly surprising when it is realizedthat amino acids-"are known in the'detergent and surface-active'fields onlyas intermediates or'add'itives. More specifically, as discussed in general at pages 34-39 of Surface-ActiveAgents,-supra, the alpha-amino acids have mainly been used :as

intermediates in the-preparation of surface ac'tive agents, generally byfreaction with higher. fatty acid halides of varying structures. Furthermore,- many .of .these acid -halides :contain. additional fun'dticnalsnr. .splubilizingrrpolar. groups; other words; :the: amino acids-in themselves; are: not re: :garded: ashaving sumcientcsolubilizing andpoiar grasps t serve as eficctive surface-active: a ents..-

. heam mi: acids, as well as ther Pt esand-proteins, have: also been known as additives for in} use-the: r ew v pr p rtie x-PP??? surface activeagcntsdsee pagev 3 10f Schwartz and-Berry, supra). However thes additivesby themselves are not recognized as being efiective surface-activeagents. f 1;

Finally, the high surface-active efiects' 'ex hibited by this new alpha-amino acid as contrasted to the almost complete ineffectiveness of its straight chain isomer, alpha-aminocapric acid, at the same concentrations are all the more surprising and, in fact, contrary to the teachings of the art. For instance, it is a well recognized generalization from long-range studies of the surface-active effects exhibited by surface-active agents of known structure that at identical concentrations surface-active agents possessing a single long chain radical bonded to the polar or solubilizing group are more effective than isomeric compounds of the same carbon content possessing branched chain structures. See for instance page 389, line 22; page 392, lines 1 and 2 up; and page 394, line 3, of Schwartz and Perry, supra.

The surface activity of this new amino acid is comparable to many commercial surface-active agents usually of much higher carbon content, normally in the range 12-18 and usually 16-18 carbons. The high surface activity of this relatively short chain alpha-amino acid makes it more eflicient as a surface-active agent and represents a potential saving of longer chain hydrocarbon compounds which can be more adequately and efllciently used in other fields wherein such long chain structures are necessary, e. g. in compositions designed to make fabrics waterproof and/or water repellant.

new alpha-amino acid, in addition to its use as a surface-active agent or plant growth regulant of readily controlled minor regulatory nature, can be used in the preparation of valuable alpha-amino acid polyamides and copolyamides, for instance through conversion to the corresponding N-carboanhydride and subsequent condensation polymerization with. carbon dioxide evolution, either alone or with other alpha-aminocarboxylic acid N-carboanhydrides. This particular use is disclosed and'claimed' in greater detail in my copending application Ser. No. 778,459, filed October 7, 1947.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described for obvious modifications will occur to those skilled in the art. 1

What is claimed is:

2-amino-4,6,G-trimethylheptanoic acid.

ROBERT NEAL MACDONALD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,462,008 Snider et al. Feb. 5, 1949 2,527, 66 Ll ak et a O t 950 

